kernel/rcu/rcuscale.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Read-Copy Update module-based scalability-test facility
   4  *
   5  * Copyright (C) IBM Corporation, 2015
   6  *
   7  * Authors: Paul E. McKenney <paulmck@linux.ibm.com>
   8  */
   9
  10 #define pr_fmt(fmt) fmt
  11
  12 #include <linux/types.h>
  13 #include <linux/kernel.h>
  14 #include <linux/init.h>
  15 #include <linux/mm.h>
  16 #include <linux/module.h>
  17 #include <linux/kthread.h>
  18 #include <linux/err.h>
  19 #include <linux/spinlock.h>
  20 #include <linux/smp.h>
  21 #include <linux/rcupdate.h>
  22 #include <linux/interrupt.h>
  23 #include <linux/sched.h>
  24 #include <uapi/linux/sched/types.h>
  25 #include <linux/atomic.h>
  26 #include <linux/bitops.h>
  27 #include <linux/completion.h>
  28 #include <linux/moduleparam.h>
  29 #include <linux/percpu.h>
  30 #include <linux/notifier.h>
  31 #include <linux/reboot.h>
  32 #include <linux/freezer.h>
  33 #include <linux/cpu.h>
  34 #include <linux/delay.h>
  35 #include <linux/stat.h>
  36 #include <linux/srcu.h>
  37 #include <linux/slab.h>
  38 #include <asm/byteorder.h>
  39 #include <linux/torture.h>
  40 #include <linux/vmalloc.h>
  41 #include <linux/rcupdate_trace.h>
  42
  43 #include "rcu.h"
  44
  45 MODULE_LICENSE("GPL");
  46 MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com>");
  47
  48 #define SCALE_FLAG "-scale:"
  49 #define SCALEOUT_STRING(s) \
  50         pr_alert("%s" SCALE_FLAG " %s\n", scale_type, s)
  51 #define VERBOSE_SCALEOUT_STRING(s) \
  52         do { if (verbose) pr_alert("%s" SCALE_FLAG " %s\n", scale_type, s); } while (0)
  53 #define SCALEOUT_ERRSTRING(s) \
  54         pr_alert("%s" SCALE_FLAG "!!! %s\n", scale_type, s)
  55
  56 /*
  57  * The intended use cases for the nreaders and nwriters module parameters
  58  * are as follows:
  59  *
  60  * 1.   Specify only the nr_cpus kernel boot parameter.  This will
  61  *      set both nreaders and nwriters to the value specified by
  62  *      nr_cpus for a mixed reader/writer test.
  63  *
  64  * 2.   Specify the nr_cpus kernel boot parameter, but set
  65  *      rcuscale.nreaders to zero.  This will set nwriters to the
  66  *      value specified by nr_cpus for an update-only test.
  67  *
  68  * 3.   Specify the nr_cpus kernel boot parameter, but set
  69  *      rcuscale.nwriters to zero.  This will set nreaders to the
  70  *      value specified by nr_cpus for a read-only test.
  71  *
  72  * Various other use cases may of course be specified.
  73  *
  74  * Note that this test's readers are intended only as a test load for
  75  * the writers.  The reader scalability statistics will be overly
  76  * pessimistic due to the per-critical-section interrupt disabling,
  77  * test-end checks, and the pair of calls through pointers.
  78  */
  79
  80 #ifdef MODULE
  81 # define RCUSCALE_SHUTDOWN 0
  82 #else
  83 # define RCUSCALE_SHUTDOWN 1
  84 #endif
  85
  86 torture_param(bool, gp_async, false, "Use asynchronous GP wait primitives");
  87 torture_param(int, gp_async_max, 1000, "Max # outstanding waits per reader");
  88 torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
  89 torture_param(int, holdoff, 10, "Holdoff time before test start (s)");
  90 torture_param(int, nreaders, -1, "Number of RCU reader threads");
  91 torture_param(int, nwriters, -1, "Number of RCU updater threads");
  92 torture_param(bool, shutdown, RCUSCALE_SHUTDOWN,
  93               "Shutdown at end of scalability tests.");
  94 torture_param(int, verbose, 1, "Enable verbose debugging printk()s");
  95 torture_param(int, writer_holdoff, 0, "Holdoff (us) between GPs, zero to disable");
  96 torture_param(int, kfree_rcu_test, 0, "Do we run a kfree_rcu() scale test?");
  97 torture_param(int, kfree_mult, 1, "Multiple of kfree_obj size to allocate.");
  98
  99 static char *scale_type = "rcu";
 100 module_param(scale_type, charp, 0444);
 101 MODULE_PARM_DESC(scale_type, "Type of RCU to scalability-test (rcu, srcu, ...)");
 102
 103 static int nrealreaders;
 104 static int nrealwriters;
 105 static struct task_struct **writer_tasks;
 106 static struct task_struct **reader_tasks;
 107 static struct task_struct *shutdown_task;
 108
 109 static u64 **writer_durations;
 110 static int *writer_n_durations;
 111 static atomic_t n_rcu_scale_reader_started;
 112 static atomic_t n_rcu_scale_writer_started;
 113 static atomic_t n_rcu_scale_writer_finished;
 114 static wait_queue_head_t shutdown_wq;
 115 static u64 t_rcu_scale_writer_started;
 116 static u64 t_rcu_scale_writer_finished;
 117 static unsigned long b_rcu_gp_test_started;
 118 static unsigned long b_rcu_gp_test_finished;
 119 static DEFINE_PER_CPU(atomic_t, n_async_inflight);
 120
 121 #define MAX_MEAS 10000
 122 #define MIN_MEAS 100
 123
 124 /*
 125  * Operations vector for selecting different types of tests.
 126  */
 127
 128 struct rcu_scale_ops {
 129         int ptype;
 130         void (*init)(void);
 131         void (*cleanup)(void);
 132         int (*readlock)(void);
 133         void (*readunlock)(int idx);
 134         unsigned long (*get_gp_seq)(void);
 135         unsigned long (*gp_diff)(unsigned long new, unsigned long old);
 136         unsigned long (*exp_completed)(void);
 137         void (*async)(struct rcu_head *head, rcu_callback_t func);
 138         void (*gp_barrier)(void);
 139         void (*sync)(void);
 140         void (*exp_sync)(void);
 141         const char *name;
 142 };
 143
 144 static struct rcu_scale_ops *cur_ops;
 145
 146 /*
 147  * Definitions for rcu scalability testing.
 148  */
 149
 150 static int rcu_scale_read_lock(void) __acquires(RCU)
 151 {
 152         rcu_read_lock();
 153         return 0;
 154 }
 155
 156 static void rcu_scale_read_unlock(int idx) __releases(RCU)
 157 {
 158         rcu_read_unlock();
 159 }
 160
 161 static unsigned long __maybe_unused rcu_no_completed(void)
 162 {
 163         return 0;
 164 }
 165
 166 static void rcu_sync_scale_init(void)
 167 {
 168 }
 169
 170 static struct rcu_scale_ops rcu_ops = {
 171         .ptype          = RCU_FLAVOR,
 172         .init           = rcu_sync_scale_init,
 173         .readlock       = rcu_scale_read_lock,
 174         .readunlock     = rcu_scale_read_unlock,
 175         .get_gp_seq     = rcu_get_gp_seq,
 176         .gp_diff        = rcu_seq_diff,
 177         .exp_completed  = rcu_exp_batches_completed,
 178         .async          = call_rcu,
 179         .gp_barrier     = rcu_barrier,
 180         .sync           = synchronize_rcu,
 181         .exp_sync       = synchronize_rcu_expedited,
 182         .name           = "rcu"
 183 };
 184
 185 /*
 186  * Definitions for srcu scalability testing.
 187  */
 188
 189 DEFINE_STATIC_SRCU(srcu_ctl_scale);
 190 static struct srcu_struct *srcu_ctlp = &srcu_ctl_scale;
 191
 192 static int srcu_scale_read_lock(void) __acquires(srcu_ctlp)
 193 {
 194         return srcu_read_lock(srcu_ctlp);
 195 }
 196
 197 static void srcu_scale_read_unlock(int idx) __releases(srcu_ctlp)
 198 {
 199         srcu_read_unlock(srcu_ctlp, idx);
 200 }
 201
 202 static unsigned long srcu_scale_completed(void)
 203 {
 204         return srcu_batches_completed(srcu_ctlp);
 205 }
 206
 207 static void srcu_call_rcu(struct rcu_head *head, rcu_callback_t func)
 208 {
 209         call_srcu(srcu_ctlp, head, func);
 210 }
 211
 212 static void srcu_rcu_barrier(void)
 213 {
 214         srcu_barrier(srcu_ctlp);
 215 }
 216
 217 static void srcu_scale_synchronize(void)
 218 {
 219         synchronize_srcu(srcu_ctlp);
 220 }
 221
 222 static void srcu_scale_synchronize_expedited(void)
 223 {
 224         synchronize_srcu_expedited(srcu_ctlp);
 225 }
 226
 227 static struct rcu_scale_ops srcu_ops = {
 228         .ptype          = SRCU_FLAVOR,
 229         .init           = rcu_sync_scale_init,
 230         .readlock       = srcu_scale_read_lock,
 231         .readunlock     = srcu_scale_read_unlock,
 232         .get_gp_seq     = srcu_scale_completed,
 233         .gp_diff        = rcu_seq_diff,
 234         .exp_completed  = srcu_scale_completed,
 235         .async          = srcu_call_rcu,
 236         .gp_barrier     = srcu_rcu_barrier,
 237         .sync           = srcu_scale_synchronize,
 238         .exp_sync       = srcu_scale_synchronize_expedited,
 239         .name           = "srcu"
 240 };
 241
 242 static struct srcu_struct srcud;
 243
 244 static void srcu_sync_scale_init(void)
 245 {
 246         srcu_ctlp = &srcud;
 247         init_srcu_struct(srcu_ctlp);
 248 }
 249
 250 static void srcu_sync_scale_cleanup(void)
 251 {
 252         cleanup_srcu_struct(srcu_ctlp);
 253 }
 254
 255 static struct rcu_scale_ops srcud_ops = {
 256         .ptype          = SRCU_FLAVOR,
 257         .init           = srcu_sync_scale_init,
 258         .cleanup        = srcu_sync_scale_cleanup,
 259         .readlock       = srcu_scale_read_lock,
 260         .readunlock     = srcu_scale_read_unlock,
 261         .get_gp_seq     = srcu_scale_completed,
 262         .gp_diff        = rcu_seq_diff,
 263         .exp_completed  = srcu_scale_completed,
 264         .async          = srcu_call_rcu,
 265         .gp_barrier     = srcu_rcu_barrier,
 266         .sync           = srcu_scale_synchronize,
 267         .exp_sync       = srcu_scale_synchronize_expedited,
 268         .name           = "srcud"
 269 };
 270
 271 #ifdef CONFIG_TASKS_RCU
 272
 273 /*
 274  * Definitions for RCU-tasks scalability testing.
 275  */
 276
 277 static int tasks_scale_read_lock(void)
 278 {
 279         return 0;
 280 }
 281
 282 static void tasks_scale_read_unlock(int idx)
 283 {
 284 }
 285
 286 static struct rcu_scale_ops tasks_ops = {
 287         .ptype          = RCU_TASKS_FLAVOR,
 288         .init           = rcu_sync_scale_init,
 289         .readlock       = tasks_scale_read_lock,
 290         .readunlock     = tasks_scale_read_unlock,
 291         .get_gp_seq     = rcu_no_completed,
 292         .gp_diff        = rcu_seq_diff,
 293         .async          = call_rcu_tasks,
 294         .gp_barrier     = rcu_barrier_tasks,
 295         .sync           = synchronize_rcu_tasks,
 296         .exp_sync       = synchronize_rcu_tasks,
 297         .name           = "tasks"
 298 };
 299
 300 #define TASKS_OPS &tasks_ops,
 301
 302 #else // #ifdef CONFIG_TASKS_RCU
 303
 304 #define TASKS_OPS
 305
 306 #endif // #else // #ifdef CONFIG_TASKS_RCU
 307
 308 #ifdef CONFIG_TASKS_TRACE_RCU
 309
 310 /*
 311  * Definitions for RCU-tasks-trace scalability testing.
 312  */
 313
 314 static int tasks_trace_scale_read_lock(void)
 315 {
 316         rcu_read_lock_trace();
 317         return 0;
 318 }
 319
 320 static void tasks_trace_scale_read_unlock(int idx)
 321 {
 322         rcu_read_unlock_trace();
 323 }
 324
 325 static struct rcu_scale_ops tasks_tracing_ops = {
 326         .ptype          = RCU_TASKS_FLAVOR,
 327         .init           = rcu_sync_scale_init,
 328         .readlock       = tasks_trace_scale_read_lock,
 329         .readunlock     = tasks_trace_scale_read_unlock,
 330         .get_gp_seq     = rcu_no_completed,
 331         .gp_diff        = rcu_seq_diff,
 332         .async          = call_rcu_tasks_trace,
 333         .gp_barrier     = rcu_barrier_tasks_trace,
 334         .sync           = synchronize_rcu_tasks_trace,
 335         .exp_sync       = synchronize_rcu_tasks_trace,
 336         .name           = "tasks-tracing"
 337 };
 338
 339 #define TASKS_TRACING_OPS &tasks_tracing_ops,
 340
 341 #else // #ifdef CONFIG_TASKS_TRACE_RCU
 342
 343 #define TASKS_TRACING_OPS
 344
 345 #endif // #else // #ifdef CONFIG_TASKS_TRACE_RCU
 346
 347 static unsigned long rcuscale_seq_diff(unsigned long new, unsigned long old)
 348 {
 349         if (!cur_ops->gp_diff)
 350                 return new - old;
 351         return cur_ops->gp_diff(new, old);
 352 }
 353
 354 /*
 355  * If scalability tests complete, wait for shutdown to commence.
 356  */
 357 static void rcu_scale_wait_shutdown(void)
 358 {
 359         cond_resched_tasks_rcu_qs();
 360         if (atomic_read(&n_rcu_scale_writer_finished) < nrealwriters)
 361                 return;
 362         while (!torture_must_stop())
 363                 schedule_timeout_uninterruptible(1);
 364 }
 365
 366 /*
 367  * RCU scalability reader kthread.  Repeatedly does empty RCU read-side
 368  * critical section, minimizing update-side interference.  However, the
 369  * point of this test is not to evaluate reader scalability, but instead
 370  * to serve as a test load for update-side scalability testing.
 371  */
 372 static int
 373 rcu_scale_reader(void *arg)
 374 {
 375         unsigned long flags;
 376         int idx;
 377         long me = (long)arg;
 378
 379         VERBOSE_SCALEOUT_STRING("rcu_scale_reader task started");
 380         set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
 381         set_user_nice(current, MAX_NICE);
 382         atomic_inc(&n_rcu_scale_reader_started);
 383
 384         do {
 385                 local_irq_save(flags);
 386                 idx = cur_ops->readlock();
 387                 cur_ops->readunlock(idx);
 388                 local_irq_restore(flags);
 389                 rcu_scale_wait_shutdown();
 390         } while (!torture_must_stop());
 391         torture_kthread_stopping("rcu_scale_reader");
 392         return 0;
 393 }
 394
 395 /*
 396  * Callback function for asynchronous grace periods from rcu_scale_writer().
 397  */
 398 static void rcu_scale_async_cb(struct rcu_head *rhp)
 399 {
 400         atomic_dec(this_cpu_ptr(&n_async_inflight));
 401         kfree(rhp);
 402 }
 403
 404 /*
 405  * RCU scale writer kthread.  Repeatedly does a grace period.
 406  */
 407 static int
 408 rcu_scale_writer(void *arg)
 409 {
 410         int i = 0;
 411         int i_max;
 412         long me = (long)arg;
 413         struct rcu_head *rhp = NULL;
 414         bool started = false, done = false, alldone = false;
 415         u64 t;
 416         u64 *wdp;
 417         u64 *wdpp = writer_durations[me];
 418
 419         VERBOSE_SCALEOUT_STRING("rcu_scale_writer task started");
 420         WARN_ON(!wdpp);
 421         set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
 422         sched_set_fifo_low(current);
 423
 424         if (holdoff)
 425                 schedule_timeout_uninterruptible(holdoff * HZ);
 426
 427         /*
 428          * Wait until rcu_end_inkernel_boot() is called for normal GP tests
 429          * so that RCU is not always expedited for normal GP tests.
 430          * The system_state test is approximate, but works well in practice.
 431          */
 432         while (!gp_exp && system_state != SYSTEM_RUNNING)
 433                 schedule_timeout_uninterruptible(1);
 434
 435         t = ktime_get_mono_fast_ns();
 436         if (atomic_inc_return(&n_rcu_scale_writer_started) >= nrealwriters) {
 437                 t_rcu_scale_writer_started = t;
 438                 if (gp_exp) {
 439                         b_rcu_gp_test_started =
 440                                 cur_ops->exp_completed() / 2;
 441                 } else {
 442                         b_rcu_gp_test_started = cur_ops->get_gp_seq();
 443                 }
 444         }
 445
 446         do {
 447                 if (writer_holdoff)
 448                         udelay(writer_holdoff);
 449                 wdp = &wdpp[i];
 450                 *wdp = ktime_get_mono_fast_ns();
 451                 if (gp_async) {
 452 retry:
 453                         if (!rhp)
 454                                 rhp = kmalloc(sizeof(*rhp), GFP_KERNEL);
 455                         if (rhp && atomic_read(this_cpu_ptr(&n_async_inflight)) < gp_async_max) {
 456                                 atomic_inc(this_cpu_ptr(&n_async_inflight));
 457                                 cur_ops->async(rhp, rcu_scale_async_cb);
 458                                 rhp = NULL;
 459                         } else if (!kthread_should_stop()) {
 460                                 cur_ops->gp_barrier();
 461                                 goto retry;
 462                         } else {
 463                                 kfree(rhp); /* Because we are stopping. */
 464                         }
 465                 } else if (gp_exp) {
 466                         cur_ops->exp_sync();
 467                 } else {
 468                         cur_ops->sync();
 469                 }
 470                 t = ktime_get_mono_fast_ns();
 471                 *wdp = t - *wdp;
 472                 i_max = i;
 473                 if (!started &&
 474                     atomic_read(&n_rcu_scale_writer_started) >= nrealwriters)
 475                         started = true;
 476                 if (!done && i >= MIN_MEAS) {
 477                         done = true;
 478                         sched_set_normal(current, 0);
 479                         pr_alert("%s%s rcu_scale_writer %ld has %d measurements\n",
 480                                  scale_type, SCALE_FLAG, me, MIN_MEAS);
 481                         if (atomic_inc_return(&n_rcu_scale_writer_finished) >=
 482                             nrealwriters) {
 483                                 schedule_timeout_interruptible(10);
 484                                 rcu_ftrace_dump(DUMP_ALL);
 485                                 SCALEOUT_STRING("Test complete");
 486                                 t_rcu_scale_writer_finished = t;
 487                                 if (gp_exp) {
 488                                         b_rcu_gp_test_finished =
 489                                                 cur_ops->exp_completed() / 2;
 490                                 } else {
 491                                         b_rcu_gp_test_finished =
 492                                                 cur_ops->get_gp_seq();
 493                                 }
 494                                 if (shutdown) {
 495                                         smp_mb(); /* Assign before wake. */
 496                                         wake_up(&shutdown_wq);
 497                                 }
 498                         }
 499                 }
 500                 if (done && !alldone &&
 501                     atomic_read(&n_rcu_scale_writer_finished) >= nrealwriters)
 502                         alldone = true;
 503                 if (started && !alldone && i < MAX_MEAS - 1)
 504                         i++;
 505                 rcu_scale_wait_shutdown();
 506         } while (!torture_must_stop());
 507         if (gp_async) {
 508                 cur_ops->gp_barrier();
 509         }
 510         writer_n_durations[me] = i_max + 1;
 511         torture_kthread_stopping("rcu_scale_writer");
 512         return 0;
 513 }
 514
 515 static void
 516 rcu_scale_print_module_parms(struct rcu_scale_ops *cur_ops, const char *tag)
 517 {
 518         pr_alert("%s" SCALE_FLAG
 519                  "--- %s: nreaders=%d nwriters=%d verbose=%d shutdown=%d\n",
 520                  scale_type, tag, nrealreaders, nrealwriters, verbose, shutdown);
 521 }
 522
 523 static void
 524 rcu_scale_cleanup(void)
 525 {
 526         int i;
 527         int j;
 528         int ngps = 0;
 529         u64 *wdp;
 530         u64 *wdpp;
 531
 532         /*
 533          * Would like warning at start, but everything is expedited
 534          * during the mid-boot phase, so have to wait till the end.
 535          */
 536         if (rcu_gp_is_expedited() && !rcu_gp_is_normal() && !gp_exp)
 537                 SCALEOUT_ERRSTRING("All grace periods expedited, no normal ones to measure!");
 538         if (rcu_gp_is_normal() && gp_exp)
 539                 SCALEOUT_ERRSTRING("All grace periods normal, no expedited ones to measure!");
 540         if (gp_exp && gp_async)
 541                 SCALEOUT_ERRSTRING("No expedited async GPs, so went with async!");
 542
 543         if (torture_cleanup_begin())
 544                 return;
 545         if (!cur_ops) {
 546                 torture_cleanup_end();
 547                 return;
 548         }
 549
 550         if (reader_tasks) {
 551                 for (i = 0; i < nrealreaders; i++)
 552                         torture_stop_kthread(rcu_scale_reader,
 553                                              reader_tasks[i]);
 554                 kfree(reader_tasks);
 555         }
 556
 557         if (writer_tasks) {
 558                 for (i = 0; i < nrealwriters; i++) {
 559                         torture_stop_kthread(rcu_scale_writer,
 560                                              writer_tasks[i]);
 561                         if (!writer_n_durations)
 562                                 continue;
 563                         j = writer_n_durations[i];
 564                         pr_alert("%s%s writer %d gps: %d\n",
 565                                  scale_type, SCALE_FLAG, i, j);
 566                         ngps += j;
 567                 }
 568                 pr_alert("%s%s start: %llu end: %llu duration: %llu gps: %d batches: %ld\n",
 569                          scale_type, SCALE_FLAG,
 570                          t_rcu_scale_writer_started, t_rcu_scale_writer_finished,
 571                          t_rcu_scale_writer_finished -
 572                          t_rcu_scale_writer_started,
 573                          ngps,
 574                          rcuscale_seq_diff(b_rcu_gp_test_finished,
 575                                            b_rcu_gp_test_started));
 576                 for (i = 0; i < nrealwriters; i++) {
 577                         if (!writer_durations)
 578                                 break;
 579                         if (!writer_n_durations)
 580                                 continue;
 581                         wdpp = writer_durations[i];
 582                         if (!wdpp)
 583                                 continue;
 584                         for (j = 0; j < writer_n_durations[i]; j++) {
 585                                 wdp = &wdpp[j];
 586                                 pr_alert("%s%s %4d writer-duration: %5d %llu\n",
 587                                         scale_type, SCALE_FLAG,
 588                                         i, j, *wdp);
 589                                 if (j % 100 == 0)
 590                                         schedule_timeout_uninterruptible(1);
 591                         }
 592                         kfree(writer_durations[i]);
 593                 }
 594                 kfree(writer_tasks);
 595                 kfree(writer_durations);
 596                 kfree(writer_n_durations);
 597         }
 598
 599         /* Do torture-type-specific cleanup operations.  */
 600         if (cur_ops->cleanup != NULL)
 601                 cur_ops->cleanup();
 602
 603         torture_cleanup_end();
 604 }
 605
 606 /*
 607  * Return the number if non-negative.  If -1, the number of CPUs.
 608  * If less than -1, that much less than the number of CPUs, but
 609  * at least one.
 610  */
 611 static int compute_real(int n)
 612 {
 613         int nr;
 614
 615         if (n >= 0) {
 616                 nr = n;
 617         } else {
 618                 nr = num_online_cpus() + 1 + n;
 619                 if (nr <= 0)
 620                         nr = 1;
 621         }
 622         return nr;
 623 }
 624
 625 /*
 626  * RCU scalability shutdown kthread.  Just waits to be awakened, then shuts
 627  * down system.
 628  */
 629 static int
 630 rcu_scale_shutdown(void *arg)
 631 {
 632         wait_event(shutdown_wq,
 633                    atomic_read(&n_rcu_scale_writer_finished) >= nrealwriters);
 634         smp_mb(); /* Wake before output. */
 635         rcu_scale_cleanup();
 636         kernel_power_off();
 637         return -EINVAL;
 638 }
 639
 640 /*
 641  * kfree_rcu() scalability tests: Start a kfree_rcu() loop on all CPUs for number
 642  * of iterations and measure total time and number of GP for all iterations to complete.
 643  */
 644
 645 torture_param(int, kfree_nthreads, -1, "Number of threads running loops of kfree_rcu().");
 646 torture_param(int, kfree_alloc_num, 8000, "Number of allocations and frees done in an iteration.");
 647 torture_param(int, kfree_loops, 10, "Number of loops doing kfree_alloc_num allocations and frees.");
 648 torture_param(bool, kfree_rcu_test_double, false, "Do we run a kfree_rcu() double-argument scale test?");
 649 torture_param(bool, kfree_rcu_test_single, false, "Do we run a kfree_rcu() single-argument scale test?");
 650
 651 static struct task_struct **kfree_reader_tasks;
 652 static int kfree_nrealthreads;
 653 static atomic_t n_kfree_scale_thread_started;
 654 static atomic_t n_kfree_scale_thread_ended;
 655
 656 struct kfree_obj {
 657         char kfree_obj[8];
 658         struct rcu_head rh;
 659 };
 660
 661 static int
 662 kfree_scale_thread(void *arg)
 663 {
 664         int i, loop = 0;
 665         long me = (long)arg;
 666         struct kfree_obj *alloc_ptr;
 667         u64 start_time, end_time;
 668         long long mem_begin, mem_during = 0;
 669         bool kfree_rcu_test_both;
 670         DEFINE_TORTURE_RANDOM(tr);
 671
 672         VERBOSE_SCALEOUT_STRING("kfree_scale_thread task started");
 673         set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
 674         set_user_nice(current, MAX_NICE);
 675         kfree_rcu_test_both = (kfree_rcu_test_single == kfree_rcu_test_double);
 676
 677         start_time = ktime_get_mono_fast_ns();
 678
 679         if (atomic_inc_return(&n_kfree_scale_thread_started) >= kfree_nrealthreads) {
 680                 if (gp_exp)
 681                         b_rcu_gp_test_started = cur_ops->exp_completed() / 2;
 682                 else
 683                         b_rcu_gp_test_started = cur_ops->get_gp_seq();
 684         }
 685
 686         do {
 687                 if (!mem_during) {
 688                         mem_during = mem_begin = si_mem_available();
 689                 } else if (loop % (kfree_loops / 4) == 0) {
 690                         mem_during = (mem_during + si_mem_available()) / 2;
 691                 }
 692
 693                 for (i = 0; i < kfree_alloc_num; i++) {
 694                         alloc_ptr = kmalloc(kfree_mult * sizeof(struct kfree_obj), GFP_KERNEL);
 695                         if (!alloc_ptr)
 696                                 return -ENOMEM;
 697
 698                         // By default kfree_rcu_test_single and kfree_rcu_test_double are
 699                         // initialized to false. If both have the same value (false or true)
 700                         // both are randomly tested, otherwise only the one with value true
 701                         // is tested.
 702                         if ((kfree_rcu_test_single && !kfree_rcu_test_double) ||
 703                                         (kfree_rcu_test_both && torture_random(&tr) & 0x800))
 704                                 kfree_rcu(alloc_ptr);
 705                         else
 706                                 kfree_rcu(alloc_ptr, rh);
 707                 }
 708
 709                 cond_resched();
 710         } while (!torture_must_stop() && ++loop < kfree_loops);
 711
 712         if (atomic_inc_return(&n_kfree_scale_thread_ended) >= kfree_nrealthreads) {
 713                 end_time = ktime_get_mono_fast_ns();
 714
 715                 if (gp_exp)
 716                         b_rcu_gp_test_finished = cur_ops->exp_completed() / 2;
 717                 else
 718                         b_rcu_gp_test_finished = cur_ops->get_gp_seq();
 719
 720                 pr_alert("Total time taken by all kfree'ers: %llu ns, loops: %d, batches: %ld, memory footprint: %lldMB\n",
 721                        (unsigned long long)(end_time - start_time), kfree_loops,
 722                        rcuscale_seq_diff(b_rcu_gp_test_finished, b_rcu_gp_test_started),
 723                        (mem_begin - mem_during) >> (20 - PAGE_SHIFT));
 724
 725                 if (shutdown) {
 726                         smp_mb(); /* Assign before wake. */
 727                         wake_up(&shutdown_wq);
 728                 }
 729         }
 730
 731         torture_kthread_stopping("kfree_scale_thread");
 732         return 0;
 733 }
 734
 735 static void
 736 kfree_scale_cleanup(void)
 737 {
 738         int i;
 739
 740         if (torture_cleanup_begin())
 741                 return;
 742
 743         if (kfree_reader_tasks) {
 744                 for (i = 0; i < kfree_nrealthreads; i++)
 745                         torture_stop_kthread(kfree_scale_thread,
 746                                              kfree_reader_tasks[i]);
 747                 kfree(kfree_reader_tasks);
 748         }
 749
 750         torture_cleanup_end();
 751 }
 752
 753 /*
 754  * shutdown kthread.  Just waits to be awakened, then shuts down system.
 755  */
 756 static int
 757 kfree_scale_shutdown(void *arg)
 758 {
 759         wait_event(shutdown_wq,
 760                    atomic_read(&n_kfree_scale_thread_ended) >= kfree_nrealthreads);
 761
 762         smp_mb(); /* Wake before output. */
 763
 764         kfree_scale_cleanup();
 765         kernel_power_off();
 766         return -EINVAL;
 767 }
 768
 769 static int __init
 770 kfree_scale_init(void)
 771 {
 772         long i;
 773         int firsterr = 0;
 774
 775         kfree_nrealthreads = compute_real(kfree_nthreads);
 776         /* Start up the kthreads. */
 777         if (shutdown) {
 778                 init_waitqueue_head(&shutdown_wq);
 779                 firsterr = torture_create_kthread(kfree_scale_shutdown, NULL,
 780                                                   shutdown_task);
 781                 if (torture_init_error(firsterr))
 782                         goto unwind;
 783                 schedule_timeout_uninterruptible(1);
 784         }
 785
 786         pr_alert("kfree object size=%zu\n", kfree_mult * sizeof(struct kfree_obj));
 787
 788         kfree_reader_tasks = kcalloc(kfree_nrealthreads, sizeof(kfree_reader_tasks[0]),
 789                                GFP_KERNEL);
 790         if (kfree_reader_tasks == NULL) {
 791                 firsterr = -ENOMEM;
 792                 goto unwind;
 793         }
 794
 795         for (i = 0; i < kfree_nrealthreads; i++) {
 796                 firsterr = torture_create_kthread(kfree_scale_thread, (void *)i,
 797                                                   kfree_reader_tasks[i]);
 798                 if (torture_init_error(firsterr))
 799                         goto unwind;
 800         }
 801
 802         while (atomic_read(&n_kfree_scale_thread_started) < kfree_nrealthreads)
 803                 schedule_timeout_uninterruptible(1);
 804
 805         torture_init_end();
 806         return 0;
 807
 808 unwind:
 809         torture_init_end();
 810         kfree_scale_cleanup();
 811         return firsterr;
 812 }
 813
 814 static int __init
 815 rcu_scale_init(void)
 816 {
 817         long i;
 818         int firsterr = 0;
 819         static struct rcu_scale_ops *scale_ops[] = {
 820                 &rcu_ops, &srcu_ops, &srcud_ops, TASKS_OPS TASKS_TRACING_OPS
 821         };
 822
 823         if (!torture_init_begin(scale_type, verbose))
 824                 return -EBUSY;
 825
 826         /* Process args and announce that the scalability'er is on the job. */
 827         for (i = 0; i < ARRAY_SIZE(scale_ops); i++) {
 828                 cur_ops = scale_ops[i];
 829                 if (strcmp(scale_type, cur_ops->name) == 0)
 830                         break;
 831         }
 832         if (i == ARRAY_SIZE(scale_ops)) {
 833                 pr_alert("rcu-scale: invalid scale type: \"%s\"\n", scale_type);
 834                 pr_alert("rcu-scale types:");
 835                 for (i = 0; i < ARRAY_SIZE(scale_ops); i++)
 836                         pr_cont(" %s", scale_ops[i]->name);
 837                 pr_cont("\n");
 838                 firsterr = -EINVAL;
 839                 cur_ops = NULL;
 840                 goto unwind;
 841         }
 842         if (cur_ops->init)
 843                 cur_ops->init();
 844
 845         if (kfree_rcu_test)
 846                 return kfree_scale_init();
 847
 848         nrealwriters = compute_real(nwriters);
 849         nrealreaders = compute_real(nreaders);
 850         atomic_set(&n_rcu_scale_reader_started, 0);
 851         atomic_set(&n_rcu_scale_writer_started, 0);
 852         atomic_set(&n_rcu_scale_writer_finished, 0);
 853         rcu_scale_print_module_parms(cur_ops, "Start of test");
 854
 855         /* Start up the kthreads. */
 856
 857         if (shutdown) {
 858                 init_waitqueue_head(&shutdown_wq);
 859                 firsterr = torture_create_kthread(rcu_scale_shutdown, NULL,
 860                                                   shutdown_task);
 861                 if (torture_init_error(firsterr))
 862                         goto unwind;
 863                 schedule_timeout_uninterruptible(1);
 864         }
 865         reader_tasks = kcalloc(nrealreaders, sizeof(reader_tasks[0]),
 866                                GFP_KERNEL);
 867         if (reader_tasks == NULL) {
 868                 SCALEOUT_ERRSTRING("out of memory");
 869                 firsterr = -ENOMEM;
 870                 goto unwind;
 871         }
 872         for (i = 0; i < nrealreaders; i++) {
 873                 firsterr = torture_create_kthread(rcu_scale_reader, (void *)i,
 874                                                   reader_tasks[i]);
 875                 if (torture_init_error(firsterr))
 876                         goto unwind;
 877         }
 878         while (atomic_read(&n_rcu_scale_reader_started) < nrealreaders)
 879                 schedule_timeout_uninterruptible(1);
 880         writer_tasks = kcalloc(nrealwriters, sizeof(reader_tasks[0]),
 881                                GFP_KERNEL);
 882         writer_durations = kcalloc(nrealwriters, sizeof(*writer_durations),
 883                                    GFP_KERNEL);
 884         writer_n_durations =
 885                 kcalloc(nrealwriters, sizeof(*writer_n_durations),
 886                         GFP_KERNEL);
 887         if (!writer_tasks || !writer_durations || !writer_n_durations) {
 888                 SCALEOUT_ERRSTRING("out of memory");
 889                 firsterr = -ENOMEM;
 890                 goto unwind;
 891         }
 892         for (i = 0; i < nrealwriters; i++) {
 893                 writer_durations[i] =
 894                         kcalloc(MAX_MEAS, sizeof(*writer_durations[i]),
 895                                 GFP_KERNEL);
 896                 if (!writer_durations[i]) {
 897                         firsterr = -ENOMEM;
 898                         goto unwind;
 899                 }
 900                 firsterr = torture_create_kthread(rcu_scale_writer, (void *)i,
 901                                                   writer_tasks[i]);
 902                 if (torture_init_error(firsterr))
 903                         goto unwind;
 904         }
 905         torture_init_end();
 906         return 0;
 907
 908 unwind:
 909         torture_init_end();
 910         rcu_scale_cleanup();
 911         if (shutdown) {
 912                 WARN_ON(!IS_MODULE(CONFIG_RCU_SCALE_TEST));
 913                 kernel_power_off();
 914         }
 915         return firsterr;
 916 }
 917
 918 module_init(rcu_scale_init);
 919 module_exit(rcu_scale_cleanup);